This thesis examines the internal politics of the Labour party during the Second World War. There are two primary elements to the study: on the one hand, an analysis of the techniques of party management, and, on the other, examination of the personal conflicts and rivalries which dominated Labour's war. The thesis considers the way in which the party's leadership group performed a delicate balancing act to prepare the ground for entry into office in an eventual coalition during the 'phoney' war of September 1939 to May 1940, continually strengthening their bargaining position while working to keep the Labour party itself subordinate to their authority and establish the primacy of their own decision making. The key figure in this was the party leader, Clement Attlee. The thesis then analyses how, once Labour entered the Churchill Coalition, its leaders again worked to preserve their strategy of membership of the government by expanding their own power and influence during five years of internal upheavals. But their course was an unpopular one, and provoked much disaffection within the party's ranks. All the while, Labour's internal politics were shaped by a series of personal conflicts and rivalries, animated by competing ambitions and enmities. The most significant was the long-running struggle for the leadership itself, between Attlee and the heir apparent, Herbert Morrison. The thesis focuses upon a wide range of individual actors, but Attlee is central: examining the way in which Attlee controlled his party, established his authority, and sought to expand his influence within government, while simultaneously struggling against his great rival Morrison, the thesis is essentially a study in the leadership of this most impenetrable, yet skilled, of politicians. Considering the language and rhetoric which the party's senior figures used to steer their course and retain the backing of their followers, as well as devoting close attention to the manoeuvre, intrigue, and pursuit of personal vendettas which impacted upon Labour politics between 1939 and 1945, the thesis argues that power-political interpretations of the period are more useful than explanations which look to ideological conflict. It also questions how far sociological change, in particular national 'emergency' and wartime radicalisation, really altered the attitudes of the British political elite.